Next.js 15 Fullstack (App Router + Server Actions) · Lesson

E2E with Playwright/Cypress

Implement end-to-end tests using tools like Playwright or Cypress to simulate user interactions and validate full application flows.

E2E with Playwright/Cypress is a free Next.js 15 Fullstack (App Router + Server Actions) lesson on CoddyKit — lesson 3 of 4. You can read the complete lesson below for free — then practise it hands-on in the browser with a built-in code editor and a 24/7 AI tutor. It is part of the Next.js 15 Fullstack (App Router + Server Actions) learning path, one of 4 lessons in the course, and your progress syncs across the web and the CoddyKit app.

What is End-to-End Testing?

End-to-End (E2E) testing simulates a real user's journey through your application, from start to finish. It tests the entire flow, including the UI, database, network requests, and server logic.

Think of it as ensuring all the pieces of your Next.js application work together seamlessly, just like a user would expect.

Why E2E for Next.js?

For Next.js applications, E2E testing is crucial because they often involve complex interactions between client and server components, API routes, and external services.

Verifies Integrations: Checks if different parts (frontend, backend, database) communicate correctly.
User Experience: Ensures critical user flows, like login or checkout, function as intended.
Confidence: Provides high confidence that new features or changes haven't broken existing functionality.

Introducing Playwright

While Cypress is another popular choice, we'll focus on Playwright for E2E testing in Next.js. Playwright is a powerful open-source framework from Microsoft that enables reliable end-to-end testing.

Key features:

Supports all modern browsers (Chromium, Firefox, WebKit).
Fast and reliable test execution.
Auto-waits for elements to be ready.
Rich set of APIs for interacting with web pages.

Setting Up Playwright

Getting Playwright ready in your Next.js project is straightforward. You'll typically run an initialization command that sets up the necessary files and installs browser binaries.

Open your terminal in your Next.js project and run:

npm init playwright@latest

Your First E2E Test

Let's write a basic test to navigate to your application's homepage and verify its title. Playwright tests are written using a test runner similar to Jest.

After setup, you'll find a tests/example.spec.ts file. Modify it:

import { test, expect } from '@playwright/test';

test('homepage has title', async ({ page }) => {
  await page.goto('http://localhost:3000/');
  await expect(page).toHaveTitle(/Next.js App/);
});

Interacting with UI Elements

Playwright allows you to simulate user actions like clicking buttons or typing into input fields. You select elements using CSS selectors, text content, or specific roles.

Here's how to fill an input and click a button:

import { test, expect } from '@playwright/test';

test('user can interact with elements', async ({ page }) => {
  await page.goto('http://localhost:3000/contact'); // Assume a contact page
  await page.fill('input[name="name"]', 'Coddy Kit');
  await page.click('button[type="submit"]');
  // After clicking, we might expect a success message to appear
  await expect(page.locator('.success-message')).toBeVisible();
});

Assertions and Visibility

Assertions are key to E2E tests, verifying that your application behaves as expected. Playwright's expect provides many matchers to check element properties, text, and visibility.

Let's verify text content and visibility:

import { test, expect } from '@playwright/test';

test('elements display correct text', async ({ page }) => {
  await page.goto('http://localhost:3000/about');
  const heading = page.locator('h1');
  await expect(heading).toHaveText('About Us');
  const paragraph = page.locator('p');
  await expect(paragraph).toContainText('Our mission');
});

Testing Form Submissions

E2E tests are perfect for validating entire form submission flows, ensuring data is sent to the server, processed, and the UI updates correctly. This covers both client-side and server-side logic.

Consider a contact form:

import { test, expect } from '@playwright/test';

test('submit contact form successfully', async ({ page }) => {
  await page.goto('http://localhost:3000/contact');
  await page.fill('input[name="email"]', 'test@example.com');
  await page.fill('textarea[name="message"]', 'Hello CoddyKit!');
  await page.click('button[type="submit"]');
  await expect(page.locator('.form-status')).toHaveText('Message sent!');
});

Running Your Tests

Once your tests are written, you can easily run them from the command line. Playwright offers various options, like running tests in headless mode (without opening a browser) or with a UI for debugging.

To run all tests:

npx playwright test

E2E Best Practices

Writing effective E2E tests requires careful planning to make them robust and maintainable. Which of these are good practices?

Recap: E2E Testing

Congratulations! You've explored End-to-End testing for Next.js applications using Playwright.

E2E tests simulate real user journeys.
Playwright is a powerful tool for cross-browser E2E testing.
You learned to set up Playwright, write tests for navigation, user interaction, and form submissions.
Remember to follow best practices for robust and maintainable E2E tests.

Frequently asked questions

Is the “E2E with Playwright/Cypress” lesson free?

Yes — the full text of “E2E with Playwright/Cypress” is free to read here on the web, and the Next.js 15 Fullstack (App Router + Server Actions) course includes 4 lessons in total. To practise it interactively (a built-in code editor and a 24/7 AI tutor) and unlock the rest of the Next.js 15 Fullstack (App Router + Server Actions) course, upgrade to CoddyKit PRO.

What will I learn in “E2E with Playwright/Cypress”?

Implement end-to-end tests using tools like Playwright or Cypress to simulate user interactions and validate full application flows. You practise Next.js 15 Fullstack (App Router + Server Actions) with hands-on code you run directly in the browser, and a 24/7 AI tutor answers your questions as you work through the lesson.

Do I need any experience to start Next.js 15 Fullstack (App Router + Server Actions)?

No prior experience is required. Next.js 15 Fullstack (App Router + Server Actions) on CoddyKit is structured for beginners through advanced learners; this is — lesson 3 of 4, so you can start here or from the beginning and move at your own pace.

How long does the “E2E with Playwright/Cypress” lesson take?

Most CoddyKit lessons take about 5–10 minutes. Each one is bite-sized and interactive, so you make steady progress and pick up exactly where you left off across the web and the app.

Can I write and run code in this Next.js 15 Fullstack (App Router + Server Actions) lesson?

Yes. Every Next.js 15 Fullstack (App Router + Server Actions) lesson includes a built-in code editor, so you write and run real code right in your browser and get instant AI feedback — no local setup required.

All lessons in this course

← Back to Next.js 15 Fullstack (App Router + Server Actions)